Process for obtaining multicolor pictures



Aug. 24, 1948. P. DANLOS 2,447,687

PRESS FOR OBTIHING yM.U.|'IICO.1OR PICTURES Filed Jan. 9) 1945 Patented Aug. 24, 1948` PROCESS FOR OBTAININ G MULTICOLOR PICTURES V`Application January 9, 1945-,1Serial No.^`71,972

In'vFrance December 20, v1943 .g i

, .sennimptlic Law 690,Augusis,194e `Patent'expres December 20, 1963 @claims (el: sis-f2.)

This inventionrelates to the color-plvlOtOgphy and particularly to the production 'oi iilmsfin two, three or four colors, from photographic films carrying different photographic silverA halide images, which are torbe found, either on the same level, or on different levels,lin a singlecoating, or alternatively in superposed diiverent coatings, on the same side, or onbothsides of a transparent support, said pictures being obtained by the well known process, which comprises ^printing with positives, developing and removingv the negative silver images to obtain a composite positive silver halide image still sensitivevto'light action,

The principal o bject'of l the invention consists of a process, particularly characterized by the fact that the various silverV halide images'considered are diierentiated byan optical method, according to which said film is tobe submitted to one or more successive differential exposuresj by means of actinic excitations that may vary'irm one point to another, in such" a 'manner that, during each exposure, one oi the images' included in the iilm is wholly exposed to the eiect of light, while the others remain quite unaltered by said effect, said film being submitted, after eaclieX- posure, to a suitable treatment, the other images being subsequently,` in their turn, submitted 'to a suitable treatmentl A particular embodiment 'of said"process conl sists of a method according to 'which 'a'differential isolation or exposure is vobtainedbymeans 'of a special element which shall be called di ier entiating unit and whichy may, iorinstance, be made up by'superp'osition on "onefvfllm or "on a plurality of assembled diierent lms,"in suitablel register, of a negative of the image which is to be exposed and of the positives of the images which are not to be exposed. Each point of the composite sensitive image is exposed through the corresponding point of the differentiatingunitso that the action of actinic light willbeon each point, proportionate both to the lumination impressed and local density. `v

If said lin comprises several images to bedifferentiated, either on the same side, orV on both sides of that iilm, several differentiating units will be used, each of which corresponds'to the image to be differentiated and constituted'as above explained, said units beingVv 'utilizedsuccessively. The invention relates'equally to the different particular treatments to which said lmhasto be submitted, after each exposure', bymeans of a diierentiating unit, or vby any other means, said treatments being different according'torthe number ofY images and of colors which are to be practically.

Finally this invention comprises not only the optical differentiation process mentioned above,

and lits method oirealisation by means of said @differentiating unit'sff but also, on tl'ieV one hand,

said fdiferentiatingunits 4constituted as it has ybeen `pointed outabove and, on th'eother/hand,

'Wthcolo'red iilms designed, forl instance, formop re's's. l

Thecharacteristicfeatureof the process action'picturfs obtained by Iapplication of said f'crdingto the invention, vthat is, th Ydifferential exposure of a composite sensitive image, offers the 'advantage ,over`v the known differentiation "processes which operate either inacl'iemical way, "or'in a mechanochemical way, that it 'renders it 'possible'thei'use'of'common 'single silver halide emulsion iilr'ns in which thevarious images to be Idiiferentiated lie'on any level, even, on the same level'iri the emulsion itself [which was impossible with saidknown process, the latter'being applicable only if said' images lie on dierent levels'. With "thoseformer processes Vit was necessary, in order specification. 1 n

'toiprevent the images' from being" on the same trary; no 'such "necessity exists, though the new process enables a film coated with a plurality of emulsions to' 'be' utilized.

'The' inventi'onfandzits applications will be more easilyunderstool bythe help 'of the following The accompanying drawing, which relates to Aa' particular example, `illustrates diagrammati- 1 cally the conditionsV of the problem to be solved servation: Whena' single silver halideemulsion is exposed to light through a positive, developed,

f and the silver removed, under inactinic light, by

means of a process utilizing bichromate or' acid pota'sh permanganate'forinstance, the silver halide image thus formed is still sensitive'to' light fand its sensitivity, atany point, is a function of vthe 'concentration of th'e 'sensitive silver 'halide grains remainingat "the 'same` point; the Sresult is that 'such 'an' image may'be'developed with a of'said images A and B` at the same point.

3. complete gradation, from black to white, after a simple uniform exposure to light and without the help of a negative. It may be verified that, in that case, a uniform action of light may produce practically thesame effect as that which may be caused by different excitations at each point corresponding to printing through a negative. Everything considered, it Was easy to foresee such a result, since the concentration of grains still sensitive to light, in whatever point .of `the.I

image in question, is a function of the brightness A i of the original subject in that point. t In the fol-vv lowing co-nsiderations, the denominations brightness of the subject or concentration of sensitive grains will be used indifferently in order to'po'int out the sensitivity of the sensitive image, in whatt ever point of the subject. k,

Let us consider now a sensitive ima'gebtaine'd in such conditions, said image being exposed" to light, that is, insulated, with a sufficient luminosi- A ty; we may then observe that it will. be possible to 4 carry out the development until such a point that n the sensitive image be separated in two images,

practically identical, ther'former of said images being constituted by reduced silver and the1latter by a silver halidewhich remains still sensitive to light.` l Y Y A n The sensitive image, thus separated, may-still be considered as theaggregate of two half-iin- Vrages, the one being identical to the other. It1 will then be seen that two identical images, situated yon the same level of a single emulsion, have thus .been separated or differentiated by that process. We have .now to consider what occurs generally when, instead of two identical images, we have` f two different images, which is thecase with imu ages proceeding from different color sensations of thefsamesubject, AWe may observe immediages, that is produce actinic excitations that may vary from one point to another and, for this purpose, we shall utilize a particular element, namely ,the differentiating unit andthe object of' the considerations hereinafter developed is to specify the conditions to be fulfilled by said'unit inorder to obtain a total exposure for one of the part images without acting, in'any way, on the other. 'For' instance, in order to x the ideas on this matten the case of a bichrome ort'wo-color film will be. considered; the images to be differentiated being called respectively A'and B, and I the primitive'image which is the sum of said images A and B. Moreover, it will be supposedthat the former (image A) is to be differentiated ina state of rei duced silver, while the latter (image B) remains in a state of silver halide, still sensitive'ito light.

It will be ascertained vimmediately that the density at any pointof said image I is equal tothe sum of the respective rdensities of the two images A and B at the same point. VTaking that remark into consideration, as well as the above enunciated fact, namely that a uniform action of light on the image I involves the same effect as a Variable action produced by means of a negative on` an ordinary emulsion (not an image form),

' it maybe easily concluded therefrom that the transparencies of theA "differentiating unit,.fat any givenpoint, must be proportionaterto .the ratio A/B of the sensitivities of images Aand lB at the corresponding point, nottaking into-consideration the absolute valuesqof the sensitivities 4 More particularly and in order to give an example, if several points m, n, o, p, and so on of said image I present certain relations of birghtness A/B, equal to each other, such as .4m/Bm=An/Bn-Ao/Bo==Ap/Bp, and so on y'the transparency 0f the differentiating unit shall be the same for these various points, whatever the absolute value of the sensitiveness of said image I may be, in other respects, at the points m, n', op, and so on that is to say even if these points are comprised in very different parts ofthe subjectI, such as very dark parts or light tones.

-Moreover, ifV the quotient A/B becomes very great'atany point, it means that B is almost equal to( Zero at that point; consequently the transparency of the differentiating unit must A Ybeco'nrie very great in order to permit a total in 4solation to be applied to image A at the point in question. On the contrary, if the quotient A/B vbecomes/very small at any point, it means that A becomes almost equal to zero, from which it results that thetransparency ofA the differentiating unitf at that point vmust be as low as possible, in order to prevent any action of light Von the image B at the point in question.

AConsequently the invention, according'to which n a solution has been found tothe above enunciated problem, consists? in submitting the film carrying the images A and Bto the effect of light, by means of a particular element, such as the differential v unit mentioned above, or otherwise, in order to obtain the wholeexposure of one of said images, while the other remains unexposed.

Said differentiating unit in the case of two images A and B may be formed by the superposition ofthe negative of the image A which is to be-exposed and ofthe positive of they other 'image atelythat a uniform exposure is n ot able to cause satisfactory results,A since thev two primitive imv vages are not identical. Consequently it is necessaryrto differentially expose the sensitive limy register.

B which is not to be exposed, said positive and negativebeing optionally included in the same film or in two separated lms joined carefully in .Moreoven the following conditions must be fuli .filled` as exactly as possible:

A. yThe negatives A and B must besubmitted to light action in such a manner that, if lthere is a gradation of gray-neutral tints said gradation is to be printed identically on the negative A and on the negative B; K

B. The positive printed from negative B is to be developedto gamma=1, and submitted to light action in such a manner that its mean density will be equal to the mean density of the negative easy causes of errors, that ,condition'wheng it is fulfilled, affords a practical method of controlling the quality ofnegatives, which offers a real interest for the operator.

Thanks to the annexed drawing, whichrelates to the casel of a two-color film, it is easy to understand the problem enunciated and the conditions ,f in which` the differential unit operates. `Image I, included in thelm, is supposed tobe an; aggregate of two images of different colors:A

. represents the density,

be, transmitted at'point c, while atpoint e, the

be entirely solved.

Prin.

. -and B." The columns I and 2 of the drawing illus- --trate' respectivelythe negative NA ofthe image A and the positive PB of the image B, the sum of which forms the "differentiating unit M.

Columns 3 and 4 illustrate diagrammatically .the

image I, resulting from the combination (or sum) of the sensitive images A and B. i

Ithas been assumed, for the clearness of the description, that the sensitive images vA and B are situated in two superimposed emulsions. Vertically, in said columns, interval a--b represents thewedge, or scale of chiaroscurmprinted in A'and in-B, with the same exposure. The interval c-c'-e represents two wedges, the one situated in A being put in a certainl direction and the other situated in B in the reverse direction, .which gives the possibility of obtaining every possible value ofthe quotient A/B. In the column .5, the flux `Il irradiated from the light source has been represented. The most intense density of the nega- "tive NApis denoted by d, said-.density being, as

usual in the photographic'technology, yindicated in thesystem of the decimal logarithms (where d -is the logarithm `or opacity) and assumed to be lequal to that'of the positive PB. In the column 6, the quantities of .light transmitted bythe dif- `ferentiating unit havebeen registered and iinally the column fl gives the value of quotient A/B.

It has been ascertained that, in the interval l a-.b, as explained above, the quotient A/B remains unchanged and equal to unity and, equally, jthat in the same interval a.-b, the superposition of the corresponding elements lhaving the same j value in the negative NA and in the positive PB, gives really an area the density of which is uniform and equal to d, as required.

In the interval c'e, the quotient A/B varies between zero and the iniinityand itmay be u pointed out that, inc', namely in the'middle of said interval c-c, it becomes equal to unity,

which involves, forthe. density oi the diierentiating unit at the corresponding point, the value d. At the point c, Where the quotient A/B is almost equal to zero, the density o fthe ,difierentiating unit will reach its maximum, which pre- Athe part 1 -b o f image A, we shall verify that,

starting from an incident flux L=l d where d only `a iiux L1.=l/109l will totality of the flux L=1 10d will be transmitted.

Therefore it appears clearly that, if on the one hand, it maybe possible to reduce the quotient 1/10d suiciently in order not to print vthe image B, at at all, where its sensitivity is maximum, and,

. on. the other hand, to obtain a value of 1x10d large enough to expose completely image A at its maximum, ofsensitivity. also, the problem will being a lconstant quantity which absolute sensitiveness of image I,

^ Moreover, l depends'on the it is easy to see that d is the variable quantity of the system, 2d representing the maximum of `density, and that consequently there is a minimum value of d, above which said vproblem always. admits a solution.

Practically instead lof tainingl separately the V original negative of image A and a `positive printled to gamma=l vo i .image B, it is preferable to riinierfediaie meer@ '0f iSaid image A,

f whichqisV developed also to gamma=1with the precautions indicated above. The diierentiati ingunit. `is then printed by utilizing as a compound negativer"v f l. The 'original negative of said image B, and

l 2, The' intermediate positiver printed through the negative A, said negative and positive being accurately superimposed in register .in the printing machine, between the lightsource and the matrix nlm.l

- With that method it is possible' not only to avoid the obligation to use'two separate matrix-films ior mass production positive printing but also to f fobtainyon -the'-diii`erentiating unit different degrees of density dzwhich depend only on the time of exposure and on the gamma chosen for devel- Y- `-oping andare independent of the degree of density oftheoriginal negatives.n

Thelm, after exposure bymeans of the differentiating unit =for instance, is submitted -to 4various treatments according toy its-constitution, according to the number of-images which it carries and nally according to the colors which are to be giventov the different-images, for instance, blue-green,magenta, yellow.

After vdeveloping and-coloring'the iirst exposed image, the. other images are submitted to daylight` and 'developed-and treated then in their '.turn, in order to'obtain vthe colors required-,fon

Vaccording to circumstances, if itis necessary, an-

other image is exposed to the action of `light through another.differentiatingunit comprising `the negative corresponding-to that image and rthepositives corresponding to the remaining images, the-second.image, thus'r exposed, being'dei vveloped and suitably treated and then the other i tions may ,be repeatedseveral times. f

remaining imagesare exposed to'fthe daylight, developedand-treated; those successive opera- Practically, ifvthere are several- 'magesfto be diierentiated, several .diierentiating units are f-used,.,the constitution oi which corresponds respectively to each of said images and after each insolation, the image which has just been exposed, is developed and suitably treatedin a convenient manner, the remaining images being then submitted to a suitable treatment. v

The successive diierentiation of several images included in a sole emulsion, by an exposure in.. which light acts on the same side of the support, may require certainprecautions in order lto l prevent. the image already diierentiated and developed constituting, up to a point, an obstacle In that case, it is veloped, beiore the following insolation, into a colored element the. absorption spectrum of which assures .the passage of actinic rays.

.-.The .following examples, limiting by no means the scopev ofthe invention, and by the help of which some practical applications of said invention are examined, point out different processes which .may be applied. f y j I. Realisation of a two-color or bichroine-lm on van ordinary lmrcoated with a single silver halide emulsion.

v-Afterprinting, thro-ugh ypart positives, of the images A and B,` and developing and removing the negative silver images, the film is dried and differentially exposedthrough the diierentiating unit dened above; said lm is then developed in a developer of usual type as, for instance, a hydroquinone developer. Said lm must then lbe treated, either by mordanting and, afterwards, bytoningi or by` a process able to develop-directly vali-idear the colors by means of a color developer such as of the diethyl-'paraphenylene-diamine type.

In the first case, the Iilm in which the 'images A and B have been diierentiated, as described above, is washed and treated with asolution of potassium iodide which transforms'the silver halide constituting the image B-into iodidev of silver,` without practically acting onthe deposit ofreduced silver which constitutes the image A.

The image B is then dyed by immersing'the lm' in a solution of safranine and auramine, containing a suitable quantity of acetic acid-the excess of coloring matter is carried away by Washing, then silver iodide is eliminated in a 'hypo "fixing bath, after having taken care to-x the coloring*- lmatter on the gelatine of the emulsion by the help of a tanning bath.- It remains then to tone image A in blue-green, which is done by immersing said image in a ferrictoning bath.v IThe ferrocyanide of silver formed in the Atoningbath isthen eliminated and, afterwards, the iilm- 'must be Washed and dried.

Inthe second case, the lm in which theim'ages A and B have been Adiiierentiated is bleached,

under an inactinic lighting, in order to transform i image A into silver chloride and said images are then developed in a special developer, such as the diethyl-paraphenylene-diamine'developer, 'for instance, with the addition of a suitable coupling agent, in order to obtain the color of image A..=

The nlm is then exposed to'daylight' and image B is directly developed ina bath of the same type the coupling element of which corresponds to the color of said image B.` Itremains then to eliminate reduced silver from images A and B', which is effected by immersion in F'armers'liquor;` and finally the lm is washed and dried.

II. Production of three-color pictures on a 'lm coated with a silver halide emulsionon each iside.

Inthis case there are three elementary images: l

A, B and G, A and B being situated lnthe same emulsion coating, While C lies on the lother side of the support. The images A'and Bare differentiated as described above; image A'appears in' the state of reduced silver, while B, as well as Con the other side of the support, remainv in the V state of silver halide. The images B and C may then be treated by mordanting and dyed separately magenta and yellowfwhile A will be' treated' by the ferrocyanide toning bath, as described with" regard to the bichrome process. It is possible also, under inactinic lighting, to convertthe image A into silver chloride and to deve1opsaid`image again, always under aninactinic lighting, in a bath containing one diamine and 'a couplingv agent` in order to obtain the blue-green irr lage a;f y After bright exposure, images B and C'willbe developed, with the corresponding couplingja'gents; in

such a manner as the-colors magentaand yellow will appear directly in said images on both sides of units, instead of a single-one.

For instance the images B and Bv will beftreated by mordantingand dyeing while images `A` and A will be treated by toning.

t is also possible, by application of `a'simil-ar process,- to treat-the fourimages separately# by' means of a" diethyliparaphenyleiie-diamine` developing baththe' oxidation product ofwhichiacts V-uponthe coupling e1`ement,`p`henol or'naphthol "Io'rming thus aninsluble Acoloring element,

which is' generally somey such body as the inda- 'v mine or'the indophenol.

IV. Finally the' caseV of afthree-colorvlm `may "be contemplated, said trichrome lmfbeing obtainedl with an ordinary-single silver halide emull" sion coated lm. In ythat case, the' totalityA of thei 'colored-'sensations preceding from the subjec'ti are' registered lo'y means of part 'positives in the single emulsion and' the-composite positive silver halide imageis obtained by developing and removing the silver negative image. i After the iilm'V has been dried under inactinic 4lighting; the

` image *corresponding to fthe' blue-green sensa- '-tion'- is' exposed, vfor instance,lby"me'ans of a "diierentiating` unit which comprises not y'only negative A and positive B, but alsoipositive C.

'Exposure' is carried out on'the'-'emuls'ion` -side landlth'e time of said exposuregas well as the-following developin'ent, are controlled in order'to reduce' into'the state of metallic silver about-one third of I"the total amount of silvery salt'corresponding to grayneutral tints; stillgunder in- Y actinic' lighting, the image A isthen converted int'chloride in order tofdevelop it again with a developer producing the blue-green' coloring elementand then we are 'fagain Y before 'the same `problem'the'object ofwhich is the differentiation of" twoim-ages Bland C, the former y'(imageB) fr :orrespondin'gv to the sensation of the' magenta color proceeding from-l thefsubj'ect' and -th latter "(image C) to the sensation of` theyellowcolor.

A second differentiating unit is :then' used,

1 said matrix being obtained as described above in i the case' of a two-'color iilm.' and the film is' exposed tothe action of lighty onthe'side ofthe support of said image. yThen development is'carriedv out in an alkalinepyrogallol'developing bath,

alkalinisation being'olotainedby addition of caustic soda, in the presence of asmall quantity of v sodium sulphite, or 'even without "sodium sulph'ite the yellow coloring element isfthus formed. i' In that case, development mustA still be controlled so that about one third of the total' amount of silver halide constituting the gray'n'eutral tints will'be reduced,l The lm is brightlyexp'osed and'developed'l in a different bathwhich' produces' the magenta 'coloring element.` 'ReducedV silver is then removed by the-help of`Farmers liquor and finally Vthe lm is washed and dried.

"' that` the invention-v hereinv ed Vas `broadly as 'defined in 'the claims.

Various modifications of the several specific illustrations given by'way of exam'ple'herein-will occur to thosefskilled in the art and it isintended described vbe interpret- Iclaim:

1; E rc'icessio'rv obtaining a 'threecolor picture a support coatedA with a single-silver halide emulsion,` which processcomprises printing into said vemulsion in `registered A"superposition with three positive part pictures in's'uchimanne as to produce a composite negative-image representing the three-'positivel part pic'tures,` l developing and *removing the' negative silver'image in orderl to l"obtain a composite 'positive-silver halide` image sensitiveimagel while in registerl with a 4'differentiating unit formed by the superimposition of the negative ofthe first componentpicture to be exposed and ofthe* twoipofs'itives of 'the second and nent picture into its elementary colored picture; dierentially exposing the said lm again while in regi-ster with a second diiTerentiatin-g unit formed by the superimposition of the negative of the second component picture to be exposed and of the positive of the third component picture not to be exposed, developing the said second component picture and transforming both second and third component pictures, each into its elementary colored picture, respectively.

2. Process for obtaining three color picture on a support bearing a silver halide coating on each side of the support, which process comprises: printing in register into the coating on the rst side with first and second positive part pictures in such manner as to produce a composite negative image representing said first and second positive part pictures, and registering into the coating on the other side the third positive part picture, developing and removing the negative silver images in order to obtain on the first side a composite positive silver halide image sensitive to light; differentially exposing the said composite sensitive image while in register With a differentiating unit formed by the superimposition of the negative of the first component picture and of th'e positive of the second component picture, developing and transforming the said first component picture into its elementary -colored picture, transforming both second and third component pictures each into its elementary colored picture respectively.

3. Process for obtaining a three color picture on a support bearing a silver halide coating on each side of the support, which process comprises: printing in register into the coating on the rst side with rst and second positive part pictures in such manner as to produce a composite negative image representing said rst and second positive part pictures, and registering into the coating on the other side the third positive part picture, developing and removing the negative silver images in order to obtain on the first side a composite positive silver halide image sensitive to light: differentially exposing the said composite sensitive image While in register with a differentiating unt formed by the superimposition of the negative of the first component picture and of the positive of the second component picture, developing the said first component picture, transforming both second and third component pictures each into its elementary colored picture respectively, finally turning the first component picture into its elementary colored picture.

4. In a process for obtaining a multicolor picture on a support coated with at least one silver halide emulsion, the steps of printing into said emulsion in registered superposition with a plurality of positive part pictures in such manner as to produce a composite negative image representing said plurality of positive part pictures, developing and removing the negative silver image in order to obtain a composite positive silver halide image sensitive to light, differentially exposing the said sensitive image While in register with a differentiating unit formed by the superimposition of the negative of the first component picture to be exposed and of the positives of the remaining of said plurality of component pictures, not to be exposed, and developing and transforming the said first component picture into its elementary colored picture.

PIERRE DANLOS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date Re. 18,680 Troland 1--- Dec. 6, 1932 2,252,718 Mannes et al. Aug. 19, 1941 2,340,656 Gaspar Feb. 1, 1944 

